The present invention pertains generally to coded aperture imaging systems and more particularly to mosaicking of coded apertures.
The basic system utilizing a uniformly redundant array is disclosed in copending application Ser. No. 902,183 entitled "Coded Aperture Imaging With Uniformly Redundant Arrays" filed May 2, 1978 by Edward E. Fenimore and Thomas M. Cannon.
As disclosed in the above-referenced application, the prior art methods of coded aperture imaging have been unable to achieve good noise handling characteristics and pure delta function response with zero sidelobes to eliminate artifacts from the reconstructed image. A primary source of these artifacts results from disengagement of the autocorrelation (A) or balanced correlation function (G) with the original array during computer processing.
Moreover, imaging off-axis sources creates additional problems. As shown in FIG. 1, a source 10 which is on-axis with the aperture 12 projects a shadow 16 so that complete information of the source is provided to detector 14. As shown in FIG. 2, a source 18 is off-axis with aperture 20 and detector 22 so that complete shadow 24 is not projected onto the detector 22. Therefore, the detector 22 must be larger than the actual aperture size to insure that the detector records the entire aperture pattern from all sources within its field of view. For many applications including x-ray astronomy, large detectors are a major disadvantage due to space limitations and increased costs. Obviously, the reconstructed image is decoded with degraded resolution, if the entire image is not observed on the detector.